alfg

Minimal MP4 Parser Example

• Download MP4: https://github.com/alfg/mp4/blob/master/test/tears-of-steel.mp4?raw=true
• Run

go run mp4_example.go tears-of-steel.mp4

go run mp4_example_2.go tears-of-steel.mp4

alfg

Mac Packaging Cheatsheet

Create a component pkg from a DMG

pkgbuild --component /Volumes/ApplicationName/*.app --install-location \
    /Applications ApplicationName-Version.pkg

Install pkg from command line

alfg

#!/usr/bin/env python3
import sys
import struct

if len(sys.argv) < 2:
  print("Usage: aac_parer.py <target.aac>")
  exit()

aacfile = open(sys.argv[1], 'rb')
frame_no = 1

alfg

var mediaJSON = { "categories" : [ { "name" : "Movies",
        "videos" : [ 
		    { "description" : "Big Buck Bunny tells the story of a giant rabbit with a heart bigger than himself. When one sunny day three rodents rudely harass him, something snaps... and the rabbit ain't no bunny anymore! In the typical cartoon tradition he prepares the nasty rodents a comical revenge.\n\nLicensed under the Creative Commons Attribution license\nhttp://www.bigbuckbunny.org",
              "sources" : [ "http://commondatastorage.googleapis.com/gtv-videos-bucket/sample/BigBuckBunny.mp4" ],
              "subtitle" : "By Blender Foundation",
              "thumb" : "images/BigBuckBunny.jpg",
              "title" : "Big Buck Bunny"
            },
            { "description" : "The first Blender Open Movie from 2006",
              "sources" : [ "http://commondatastorage.googleapis.com/gtv-videos-bucket/sample/ElephantsDream.mp4" ],

alfg

Originall From: Posted 2015-05-29 http://ubwg.net/b/full-list-of-ffmpeg-flags-and-options

This is the complete list that’s outputted by ffmpeg when running ffmpeg -h full.

usage: ffmpeg [options] [[infile options] -i infile]… {[outfile options] outfile}…

Getting help:
    -h — print basic options
    -h long — print more options
    -h full — print all options (including all format and codec specific options, very long)

alfg

// NullString is an alias for sql.NullString data type
type NullString struct {
	sql.NullString
}

// MarshalJSON for NullString
func (ns *NullString) MarshalJSON() ([]byte, error) {
	if !ns.Valid {
		return []byte("null"), nil

alfg

language: bash
before_install:
- echo $super_secret_password | gpg --passphrase-fd 0 .travis/deploy.key.gpg
- eval "$(ssh-agent -s)"
- chmod 600 .travis/deploy.key
- ssh-add .travis/deploy.key
- ssh-keyscan git.host.com >> ~/.ssh/known_hosts
after_success:
- git remote add deploy dokku@git.host.com:app
- git config --global push.default simple

alfg

Instructions

Download and Install Raspbian Stretch

Get the latest copy of Raspbian Stretch from the official Raspberry Pi website and image this to your SD card.

Raspbian Stretch Lite is prefered as there is no need to run a GUI desktop.
How to install Raspberry Pi Operating System Images

alfg

## extract audio from .avi as .aac (conversion from another audio codec)
ffmpeg -i foo.avi -acodec aac -ab 128k -strict experimental bar.aac

## extract audio from .avi as .mp3 (no conversion, just copy)
ffmpeg -i foo.avi -acodec copy bar.mp3

## convert .mp3 to .aac
ffmpeg -i foo.mp3 -acodec aac -ab 128k -strict experimental bar.aac

## extract single frame as image from .mp4

alfg

Golang Workers / Job Queue

A running example of the code from:

• http://marcio.io/2015/07/handling-1-million-requests-per-minute-with-golang
• http://nesv.github.io/golang/2014/02/25/worker-queues-in-go.html

This gist creates a working example from blog post, and a alternate example using simple worker pool.

TLDR: if you want simple and controlled concurrency use a worker pool.